Pedal-operating mechanism



' Nov. 5, 1929.

C. F. STODDARD PEDAL OPERATING MECHANISM Filed June 1, 1923 2 SheetsSheet l vwcntoz (Zariesiifzbdc/ard 351 A elf 500140 NOV. 5, 1929. c STQDDARD 1,734,607

PEDAL OPERATING MECHANI S M Filed June 1, 1923 2 Sheets-Sheet 2 Patented Nov. 5, 1929 UNITED STATES PATENT OFFICE CHARLES F. STODDARD, OF NEW YORK, N. Y., ASSIGNOR TO AMERICAN PIANO COM- IPANY, OF NEW YORK, N. Y., A CORPORATION OF NEW JERSEY I PEDAL-OPERATING MECHANISM Application filed June 1, 1923. Serial No. 642,748.

This invention relates to automatic musical instruments and pertains more particularly to power pneumatics for transforming pneu matic' power from the main source of power into suitable mechanical power for operating movable parts of a piano action or any of the various expression devices.

In the ordinary type of .power pneumatic,

as the pneumatic is collapsed, the area on which the pneumatic force acts is decreased during its collapse due to the folding of the bellows cloth. The result of this action is that as the bellows is collapsed, the force which can be exerted by it is materially de creased, and for this reason larger pneumatics than would otherwise be necessary must be supplied in order to provide adequate force at the end of the stroke. It is an object of this invention, therefore, to provide. a power pneumatic in which the variable force before mentioned may be compensated by another variable, and thus provide a power pneumatic which at all positions between its extreme positions of collapse and expansion will exert a substantially constant force on the part of the piano to be moved.

It is also an object of the invention to provide means by which this variable may be so changed that the effective force of the pneumatic on parts to be moved, may assume varying relations, as for instance, the force exerted by the pneumatic may be increased as the bellows is collapsed, or it may be decreased to any desired extent.

In the drawings the preferred illustrative embodiment of the invention is shown as applied to the operation of expression mechanisms for a player piano, and therein,

Figure 1 represents semi-diagra1natically the loud and soft pedal mechanisms of the piano with the improved power pneumatic applied thereto.

Figure 2 is a side elevation of the power pneumatic showing the same in expanded position'.

Eigure 3 is a side elevation of the powe pneumatic showing the same in collapsed position.

Referring to the drawings, in the bottom of the piano casing 1 are provided the usual expression pedals 2 and 2 which are suitably connected by rods 3 and 4 and levers 5 and 6 with their respective pedal dowels 7 and 8. These dowels are connected at their upper ends with the usual expression mechanisms, the dowel 7 being pivoted at 9 to the hammer rest rail 10, and the dowel 8 being pivoted at 11 to a bell crank 12 operating the dampers 13 in a well-known manner.

The mechanisms thus far described are, of 0 course, old and well known in the art. Depression of the pedal 2 will raise dowel 8 and withdraw the dampers 13 from the strings in the usual manner. Depression of the pedal 3 will raise dowel 7 which in turn will throw the rest rail 10 forward and thus limit the travel of the hammers.

Power pneumatics 14: and 15 are mounted on the casing 1 at suitable distances from the dowels 7 and 8. Since these pneumatics are precisely the same in construction and operation, only one will be described in detail herein. Referring to Figures 2 and 3, the pneumatics consist of a fixed leaf 16 suitably fixed to the piano frame 1, and a movable leaf 17 pivoted to the fixed leaf in the usual manner. A suitable bellows cloth 18 is provided connecting the two leaves, and a con duit 19 is provided through which air may be exhausted from said pneumatic to collapserso the same.

Mounted on the movable leaf of the pneumatic is a pivot block 20 to which is pivoted at 21 a link 22 which may be suitably shaped as shown with a bulge on one side, the purposes w 5 of which will be set forth hereafter. Pivoted to the fixed leaf 16 as at 24 is a link 25. This link is in turn pivoted to the link 22 at 26. Depending from the bulge portion of the link 22, and pivoted thereto at 27 is a connect-" ing link 28 pivoted at its lower end at 29 to the pedal dowel 7 so that longitudinal motion of thelink 28 will be communicated thereto.

As set forth before, as the bellows is collapsed the area on which pneumatic force may act is decreased due to the folding of the bellows cloth. Some suitable variable must,

therefore, be introduced to compensate this decrease in force. In the present instance th s compensating var able is provided by the links 22 and 25 which serve to vary the lever arms through which the pneumatic force acts. Two lever arms must be considered, that through which the pneumatic force acts and that through which the mechanical force is transmitted. The former is represented by a perpendicular from the point 21 to a line connecting points 2 1 and 26. eferring to Figures 2 and 3 again, it will be seen that as the bellows is collapsed, this perpendicular increases in length and hence the lever arm is increased. The other lever arm is represented by a perpendicular from the point 21 to a line connecting points 27 and 29. Referring again to the drawings, it will be seen that as the bellows is collapsed, this perpendicular and hence the lever arm is decreasing in length. As will be observed, however, in the case of both levers the mechanical advantage is increased as the pneumatic is collapsed, since in the case of the first lever the arm is increasing in length as the force is applied, while in the case of the second lever the arm is decreasing in length as the force is transmitted.

In the device shown and described the points 21, 26, 27 and 29 have been so arranged with respect to each other, that the two vary ing lever arms will compensate the decrease in pneumatic force in order to maintain the resulting force supplied to the dowel substantially constant. Obviously, however, the invention is susceptible of other adjustments. For instance. it may be desirable in some cases to increase the force exerted by the pneumatic during its colla se. In such case a simple rearrangement o the pivots to secure a larger increase in moment would. give the desired result.

It will be understood by those skilled in the art that the invention herein described is not limited to the particular form or combination of parts herein shown and described or the particular application thereof. The invention is susceptible of use for instance wherever it is desired to use a power pneumatic. On the contrary, the invention may be variably modified and embodied within the scope of the subjoined claims.

I claim as my invention:

1. In an automatic musical instrument, a power pneumatic; means through which said pneumatic may be collapsed; and means whereby the force exerted by said pneumatic is maintained substantially constant throughout its collapsing movement.

2. In an automatic musical instrument, a

power pneumatic; means actuated by said power pneumatic; means through which said pneumatic may be collapsed; and means whereby the force exerted by said power pneumatic on said actuated means is maintaind substantially constant throughout the collapsing movement of the pneumatic.-

3. A power pneumatic for automatic musical instruments, comprising, in combination, a fixed leaf a movable leaf; an actuated means; and means connecting said leaves to said actuated means such that a substantially constant force is applied to said actuated means during collapsing movement of said movable leaf.

In testimony whereof, I have signed my name to this specification this 24th day of May, 1923. r h

' CHARLES F. STODDARD. 

